Most of wireless communication systems including a Mobile WiMAX system perform a terminal power saving procedure according to characteristics and wireless environment of the corresponding system. For example, an idle mode and a sleep mode are introduced to minimize power consumption in the Mobile WiMAX system.
In a protocol negotiation procedure between a terminal and a base station to enter the idle mode, a Paging Listen Interval (PLI) and a Paging Unavailable Interval (PUI) are determined. To receive a paging message received from the base station in the PLI negotiated with the base station, the terminal changes some or all of components inactive during the PUI to an active mode before the PLI starts to thus receive the paging message in the PLI. Herein, to the receive the paging message in the PLI, the base station selected by the terminal is referred to as a Preferred Base Station (PBS).
Meanwhile, in the Mobile WiMAX system using a single frequency, a frequency selected in the previous PLI is used without considering frequencies of neighbor base stations when the terminal of the idle mode selects the PBS. Herein, the time required for the terminal in the corresponding idle mode to synchronize for the PBS selection based on a location of the terminal may vary according to downlink channel quality. That is, in the single-frequency network environment, a terminal close to the base station attains the good downlink signal quality (hereafter, referred to as a strong electric field) and requires a relatively short time in the synchronization to select the PBS, and a terminal in a cell boundary far away from the BS (hereafter, referred to as a weak electric field) requires a relatively long time in the synchronization to select the PBS.
In a network using multiple frequencies, to select the PBS, the idle-mode terminal needs to scan some or all of the frequencies defined in the corresponding network (hereafter, referred to as a frequency selection procedure) prior to the synchronization.
In recent, most of the wireless communication systems includings the Mobile WiMAX system define only an idle mode pattern (paging cycle, paging offset, etc.) between the terminal and the bases station and information required to update the location.
That is, conventional techniques merely describe a basic operation for receiving the paging message in the designated PLI, and do not define any operation for minimizing the power consumption of the terminal in the PUI, not in the PLI.
The power saving mode suggested in the mobile communication system provides a method of the corresponding mobile station to minimize its power in the PUI by combining the PLI and the PUI. However, each system does not define which operation the mobile station performs in the PUI. Accordingly, the method for enhancing the terminal power use efficiency in the power saving mode suggested by each system is the very important issue in terms of the individual terminal manufacturer.
Hence, a method and an apparatus for efficiently reducing the power consumption of the terminal during the idle mode in the wireless communication system are demanded.